//uniform float     iTimeDelta;            // render time (in seconds)
//uniform float     iFrameRate;            // shader frame rate
//uniform float     iChannelTime[4];       // channel playback time (in seconds)
//uniform vec3      iChannelResolution[4]; // channel resolution (in pixels)
//uniform vec4      iMouse;                // mouse pixel coords. xy: current (if MLB down), zw: click
////uniform samplerXX iChannel0..3;          // input channel. XX = 2D/Cube
//uniform vec4      iDate;                 // (year, month, day, time in seconds)

uniform vec2 _ScreenSize;
uniform vec4 _Time;

uniform sampler2D iChannel0;
uniform sampler2D iChannel1;
uniform sampler2D iChannel2;
uniform sampler2D iChannel3;

uniform int iFrame;

#define iResolution _ScreenSize
#define iTime _Time.y
